BACKGROUND: We aimed to explore the effect of intraoperative S-ketamine on analgesic consumption and pain one year after spine surgery in chronic opioid-dependent patients undergoing spinal fusion surgery.

METHODS: Single-centre, randomized, blinded trial of 147 patients.

INTERVENTION: Perioperative S-ketamine bolus 0.5 mg/kg followed by S-ketamine 0.25 mg kg-1 hr-1 infusion or placebo.

MAIN OUTCOMES: Analgesic use, pain (visual analogue scale 0-100 mm [VAS]) and labour market attachment one year after surgery assessed by written questionnaires.

RESULTS: Response rate was 67%. One year after surgery, the daily use of oral morphine equivalents was lower in the ketamine group versus the placebo group: 0 (0-20) mg versus 20 (0-62) mg, (p = 0.02), and fewer patients had a daily use of any analgesics in the ketamine group versus placebo group, 42% (95% CI 23-61) versus 74% (95% CI 58-87), (p = 0.04). Mobilization pain was lower in the ketamine group compared to the placebo group: Median difference 17 mm (95% CI -30 to -3), (p = 0.02). Pain at rest was lower in the ketamine group compared to the placebo group with median difference: 13 mm (95% CI -23 to -3), (p = 0.01). Further, labour market attachment was better in the ketamine group, (p = 0.02).

CONCLUSION: Intraoperative ketamine may reduce analgesic use, pain, and improve labour market attachment one year after spine surgery in a chronic opioid-dependent population.

SIGNIFICANCE: This randomized clinical trial shows that intraoperative ketamine may reduce opioid use and pain and improve labour market attachment one year after spine surgery in an opioid-dependent population.